Maladaptive migration behaviour in hybrids links to predator-mediated ecological selection

Area of Science:

• Ecology
• Evolutionary Biology
• Behavioral Ecology

Background:

• Species-specific migratory traits enhance fitness within ecological niches.
• Hybridization can lead to maladaptive combinations of migratory traits, potentially impacting hybrid viability and species integrity.

Purpose of the Study:

• To investigate migratory behavior in natural fish hybrids and their parental species.
• To explore the relationship between migratory traits and predation risk in these populations.

Main Methods:

• Utilized electronic tags and passive telemetry to track individual migration patterns (timing, trip frequency) in roach, bream, and their hybrids.
• Monitored regurgitated tags from great cormorants at roosting sites to assess predation events linked to migratory behavior.

Main Results:

• Hybrids displayed more frequent, shorter migratory trips between lake and stream habitats compared to parental species.
• Hybrid departure timing was bimodal, overlapping parental averages, while parental species had distinct departure dates.
• Increased multi-trip movement frequency correlated with higher predation probability by cormorants, with hybrids experiencing greater predation risk.

Conclusions:

• Maladaptive migratory behavior in hybrids increases their exposure to predators.
• Predator-mediated selection acting on migratory traits can reduce hybrid survival, thereby reinforcing species integrity.
• This study offers novel insights into hybrid viability and the role of ecological selection in maintaining species boundaries.